Insight into the Primary and Secondary Particle-Bound Methoxyphenols and Nitroaromatic Compound Emissions from Solid Fuel Combustion and the Updated Source Tracers

• DOI: 10.1021/acs.est.3c04370
• Publication Date: 2023-09-14T17:26:03Z
• Authors: Bin Zhang; Zhenxing Shen; Kun He; Jian Sun; Shasha Huang; Hongmei Xu; Jianjun Li; Steven Sai Hang Ho; Jun-ji Cao
• Keywords: Guaiacol; Syringic acid; Syringaldehyde

Methoxyphenols and nitroaromatic compounds (NACs) have strong atmospheric radiative forcing effects adverse on human health. They are emitted from the incomplete combustion of solid fuels secondarily formed through photochemical reactions. Here, an on-site study was conducted to determine primary emission secondary formation particulate phase products a variety potential aerosol mass-oxidation flow reactor. Emission factors for total quantified methoxyphenols NACs (i.e., EF∑Methoxyphenols EF∑NACs) varied by 2 orders magnitude among different fuels, which were greatly influenced volatile matter, combustibility, flame intensity, temperature. Guaiacol 4-nitro-2-vinylphenol used as tracers organic due low aged-to-fresh ratios (0.21-0.97), while 4-methyl-guaiacol, 4-ethyl-guaiacol, eugenol, 4-methyl-syringol, isoeugenol, acetovanillone, syringaldehyde, homovanillin acid, vanillin syringic acid identified (SOA) (aged-to-fresh between 1.90 4.20). During simulated aging, -CHO group reacted with hydroxyl radical (•OH) form -COOH group, but there no correlation syringol 4-nitrosyringol, implying that •OH is main reactant rather than nitriate (•NO3) in aging processes methoxyphenols. Aging caused substantially profiles variable reaction properties. The fresh EFs guaiacol biomass burning ranged 3.80 ± 0.44 26.2 5.40 mg·kg-1, much higher those coal combustions (of 0.03 0.01 1.42 0.28 mg·kg-1). However, aged (EFaged) 1.02 0.06 1.61 0.11 mg·kg-1 most combustions, comparable bituminous chunk (1.20 0.16 Therefore, guaiacol, traditional marker, not ideal tracer PM2.5 burning. Indeed, syringol/guaiacol syringol/4-nitrosyringol found be more suitable efficient source characterization.